The cephalosporin antibiotic 7-[2-(2-amino-1,3-thiazol-4-yl)-2-methoxyimino)acetamido]-3-[(fur-2-ylcarb onyl)thiomethyl]-3-cephem-4-carboxylic acid (also named 7-[2-(2-amino-4-thiazolyl)-2-methoxyimino)-acetamido]-3-[2-(furanylcarbony lthiomethyl)-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-1-carboxylic acid) (2), its alkali metal, alkaline earth metal and amine salts of the carboxylic acid group, and easily hydrolyzable ester groups thereof are described and claimed in Labeeuw et al U.S. Pat. No. 4,464,367. This cephalosporin free acid (2) compound is now known by the generic name ceftiofur, in France.
Those free acid and cationic metal and amine salt and ester forms of this cephalosporin antibiotic are somewhat unstable chemically and are obtained as amorphous compounds which are difficult to purify, and are less desirable to work with in manufacturing pharmaceutical formulations containing them. Those patented salts thus create salt-solid-isolation and salt-solid-handling problems in a pharmaceutical manufacturing plant which those in the pharmaceutical art would prefer to avoid. However, it is not predictable how to make useful crystalline salt forms of any particular active drug cephalosporin compound.